The present invention relates to an optical fiber connector for optical communications applications and, more particularly, to a non-rotation type optical fiber connector which allows easy coupling and uncoupling manipulations and provides a secure connection.
Connection between a pair of optical fibers and/or between an optical fiber and an optical component, such as a light emitting, or light receiving element has been implemented by various kinds of optical fiber connectors. One type of such connectors comprises a pair of plugs which are each fixed to an end of an optical fiber, and an adaptor through which the opposite optical fibers are interconnected with the optical axes of the plugs aligned. For the connection of an optical fiber with a light emitting or light receiving element, the plugs are inserted into a receptacle in which the light emitting or light receiving element is built. In this kind of optical fiber connector, the primary requisite is that the plugs must be detachably coupled with the adaptor or with the receptacle.
The connectors heretofore proposed may generally be classified into three typical types, i.e., a threaded connection type, a bayonet connection (BNC) type, and a non-rotation connection type. Among them, although the non-rotation type is inferior to the threaded type concerning the secureness of coupling, it has been extensively used as simple connector coupling means partly because it allows the plugs and the adaptor or the receptacle to be coupled by easy manipulation.
Referring to FIGS. 1 and 2, side elevation of a prior art optical fiber connector of the non-rotation type is shown. In FIG. 1, a plug and an adaptor of the connector are shown in an uncoupled position and, in FIG. 2, in a coupled position.
An adaptor 1 has a generally rectangular end portion (unnumbered) which is provided with recesses or grooves 5 and a projection 3 emerging from the recesses 5. The projection 3 has tapered portions 3a and 3b at opposite ends thereof. A plug 2 includes a ferrule 8 fixed to an end of an optical fiber cord 13 and securely accommodating therein an optical fiber which extends through the cord 13, and a housing 6 in which the ferrule 8 is disposed. A pair of elastic arms 6a extend from the housing 6 toward the tip of the ferrule 8 in parallel to the center axis of the ferrule 8 and each is provided with a pawl 4 at its free end. The pawls 4 are each provided with tapered portions 4a and 4b which will make contact with and mate with the tapered portions 3a and 3b of the adaptor projection 3 when the plug 2 is coupled with the adaptor 1.
When the ferrule 8 is inserted into the adaptor 1, the tapered portions 4a of the pawls 4 abut against the respective tapered portions 3a of the adaptor projection 3. As the ferrule 8 is thrusted deeper into the adaptor 1, the elastic arms 6a of the plug 6 are urged away from each other until they reach the recesses 5 of the adaptor 1. Then, the arms 6a spring back toward each other so that the pawls 4 mate with the respective recesses 5 as shown in FIG. 2, in which the tapered sections 3b and 4b are engaged with each other.
To uncouple the connector, the plug 2 is pulled away from the adaptor 1. This urges the elastic arms 6a away from each other with the tapered portions 4b sliding on the associated tapered portions 3b, until the plug 2 becomes clear of the adaptor 1.
Due to the above construction, when forces act on the plug 2 and the adaptor 1 in opposite directions, they are apt to spread the elastic arms 6a of the housing 6 away from each other causing the plug 2 to easily and unwantedly slip off the adaptor 1. This drawback may be coped with by, for example, thickening the elastic arms 6a to prevent them from easily moving away from each other, or increasing the mating depth of the pawls 4 with the recesses 5, or omitting all the tapered portions 4a and 4b of the pawls 4 and those 3a and 3b of the adaptor projection 3. All such schemes, however, would make manipulations for coupling and uncoupling the adaptor 1 and plug 2 troublesome.
It will be seen from the above that the prior art non-rotation type connector cannot readily attain a sufficiently great coupling force while facilitating easy coupling and uncoupling operations, that is, one of the two requisites can be satisfied only at the sacrifice of the other. Especially, where an optical fiber has a small diameter core or provided with a cable sheath whose resistance to bending is substantial, it is hard to accomplish reliable coupling by means of the prior art connector of the type concerned.